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NVD / CVE Program· CNA Linux

CVE-2023-53673: Bluetooth: hci_event: call disconnect callback before deleting conn

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.25% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 093a07052406b363b1b2ab489e17dbadaf3e509b, 1ecf6dc2676ead4b927c50b1be0851fa4d756574, 59bd1e476bbc7bc6dff3c61bba787095a4839796.

Low priority for now. Upgrade to Linux Linux 093a07052406b363b1b2ab489e17dbadaf3e509b, 1ecf6dc2676ead4b927c50b1be0851fa4d756574, 59bd1e476bbc7bc6dff3c61bba787095a4839796 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_event: call disconnect callback before deleting conn In hci_cs_disconnect, we do hci_conn_del even if disconnection failed. ISO, L2CAP and SCO connections refer to the hci_conn without hci_conn_get, so disconn_cfm must be called so they can clean up their conn, otherwise use-after-free occurs. ISO: ========================================================== iso_sock_connect:880: sk 00000000eabd6557 iso_connect_cis:356: 70:1a:b8:98:ff:a2 -> 28:3d:c2:4a:7e:da ... iso_conn_add:140: hcon 000000001696f1fd conn 00000000b6251073 hci_dev_put:1487: hci0 orig refcnt 17 __iso_chan_add:214: conn 00000000b6251073 iso_sock_clear_timer:117: sock 00000000eabd6557 state 3 ... hci_rx_work:4085: hci0 Event packet hci_event_packet:7601: hci0: event 0x0f hci_cmd_status_evt:4346: hci0: opcode 0x0406 hci_cs_disconnect:2760: hci0: status 0x0c hci_sent_cmd_data:3107: hci0 opcode 0x0406 hci_conn_del:1151: hci0 hcon 000000001696f1fd handle 2560 hci_conn_unlink:1102: hci0: hcon 000000001696f1fd hci_conn_drop:1451: hcon 00000000d8521aaf orig refcnt 2 hci_chan_list_flush:2780: hcon 000000001696f1fd hci_dev_put:1487: hci0 orig refcnt 21 hci_dev_put:1487: hci0 orig refcnt 20 hci_req_cmd_complete:3978: opcode 0x0406 status 0x0c ... <no iso_* activity on sk/conn> ... iso_sock_sendmsg:1098: sock 00000000dea5e2e0, sk 00000000eabd6557 BUG: kernel NULL pointer dereference, address: 0000000000000668 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014 RIP: 0010:iso_sock_sendmsg (net/bluetooth/iso.c:1112) bluetooth ========================================================== L2CAP: ================================================================== hci_cmd_status_evt:4359: hci0: opcode 0x0406 hci_cs_disconnect:2760: hci0: status 0x0c hci_sent_cmd_data:3085: hci0 opcode 0x0406 hci_conn_del:1151: hci0 hcon ffff88800c999000 handle 3585 hci_conn_unlink:1102: hci0: hcon ffff88800c999000 hci_chan_list_flush:2780: hcon ffff88800c999000 hci_chan_del:2761: hci0 hcon ffff88800c999000 chan ffff888018ddd280 ... BUG: KASAN: slab-use-after-free in hci_send_acl+0x2d/0x540 [bluetooth] Read of size 8 at addr ffff888018ddd298 by task bluetoothd/1175 CPU: 0 PID: 1175 Comm: bluetoothd Tainted: G E 6.4.0-rc4+ #2 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x5b/0x90 print_report+0xcf/0x670 ? __virt_addr_valid+0xf8/0x180 ? hci_send_acl+0x2d/0x540 [bluetooth] kasan_report+0xa8/0xe0 ? hci_send_acl+0x2d/0x540 [bluetooth] hci_send_acl+0x2d/0x540 [bluetooth] ? __pfx___lock_acquire+0x10/0x10 l2cap_chan_send+0x1fd/0x1300 [bluetooth] ? l2cap_sock_sendmsg+0xf2/0x170 [bluetooth] ? __pfx_l2cap_chan_send+0x10/0x10 [bluetooth] ? lock_release+0x1d5/0x3c0 ? mark_held_locks+0x1a/0x90 l2cap_sock_sendmsg+0x100/0x170 [bluetooth] sock_write_iter+0x275/0x280 ? __pfx_sock_write_iter+0x10/0x10 ? __pfx___lock_acquire+0x10/0x10 do_iter_readv_writev+0x176/0x220 ? __pfx_do_iter_readv_writev+0x10/0x10 ? find_held_lock+0x83/0xa0 ? selinux_file_permission+0x13e/0x210 do_iter_write+0xda/0x340 vfs_writev+0x1b4/0x400 ? __pfx_vfs_writev+0x10/0x10 ? __seccomp_filter+0x112/0x750 ? populate_seccomp_data+0x182/0x220 ? __fget_light+0xdf/0x100 ? do_writev+0x19d/0x210 do_writev+0x19d/0x210 ? __pfx_do_writev+0x10/0x10 ? mark_held_locks+0x1a/0x90 do_syscall_64+0x60/0x90 ? lockdep_hardirqs_on_prepare+0x149/0x210 ? do_syscall_64+0x6c/0x90 ? lockdep_hardirqs_on_prepare+0x149/0x210 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7ff45cb23e64 Code: 15 d1 1f 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 80 3d 9d a7 0d 00 00 74 13 b8 14 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 89 54 24 1c 48 89 RSP: 002b:00007fff21ae09b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: ---truncated---

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Oct 7, 2025
Updated
Aug 5, 2026
EPSS
0.2% · 16th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.8
CNA · Linux
8.8
1.0 point gap

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.7 and later · before 5.15.200
  • linux linux kernel5.16 and later · before 6.1.42
  • linux linux kernel6.2 and later · before 6.4.7
  • linux linux kernel6.5

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.7affected
    • b8d290525e3972b5e876b2649a42bf4081d753fe and later · before 1ecf6dc2676ead4b927c50b1be0851fa4d756574affected · git
    • b8d290525e3972b5e876b2649a42bf4081d753fe and later · before 59bd1e476bbc7bc6dff3c61bba787095a4839796affected · git
    • b8d290525e3972b5e876b2649a42bf4081d753fe and later · before 093a07052406b363b1b2ab489e17dbadaf3e509baffected · git
    • b8d290525e3972b5e876b2649a42bf4081d753fe and later · before 7f7cfcb6f0825652973b780f248603e23f16ee90affected · git
    • before 5.7not affected · semver
    • 5.15.200 and later · up to and including 5.15.*not affected · semver
    • 6.1.42 and later · up to and including 6.1.*not affected · semver
    • 6.4.7 and later · up to and including 6.4.*not affected · semver
    • 6.5 and laternot affected · original_commit_for_fix

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8bpftoolbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernelbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-abi-stablelistsbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-corebefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-cross-headersbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-debugbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-debug-corebefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-debug-develbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-debug-modulesbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-debug-modules-extrabefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-develbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-docbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-headersbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-modulesbefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-modules-extrabefore 4.18.0-553.97.1.el8_104.18.0-553.97.1.el8_10
AlmaLinux:8kernel-rtbefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10
AlmaLinux:8kernel-rt-corebefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10
AlmaLinux:8kernel-rt-debugbefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10
AlmaLinux:8kernel-rt-debug-corebefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10
AlmaLinux:8kernel-rt-debug-develbefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10
AlmaLinux:8kernel-rt-debug-modulesbefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10
AlmaLinux:8kernel-rt-debug-modules-extrabefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10
AlmaLinux:8kernel-rt-develbefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10
AlmaLinux:8kernel-rt-modulesbefore 4.18.0-553.97.1.rt7.438.el8_104.18.0-553.97.1.rt7.438.el8_10

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2023-53671Oct 7, 2025 · srcu: Delegate work to the boot cpu if using SRCU_SIZE_SMALL
    22Monitor
  • ← EarlierCVE-2023-53672Oct 7, 2025 · btrfs: output extra debug info if we failed to find an inline backref
    22Monitor
  • Later →CVE-2022-50528Oct 7, 2025 · drm/amdkfd: Fix memory leakage
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux093a07052406b363b1b2ab489e17dbadaf3e509bVendor (CNA)
Linux Linux1ecf6dc2676ead4b927c50b1be0851fa4d756574Vendor (CNA)
Linux Linux59bd1e476bbc7bc6dff3c61bba787095a4839796Vendor (CNA)
Linux Linux7f7cfcb6f0825652973b780f248603e23f16ee90Vendor (CNA)
almalinux:bpftool4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-abi-stablelists4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-core4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-cross-headers4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-core4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-devel4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules-extra4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-devel4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-doc4.18.0-553.97.1.el8_10 · AlmaLinux:8Package registry (OSV)
debian:linux6.1.52-1 · Debian:12Package registry (OSV)
red hat:bpftool0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:bpftool-debuginfo0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-abi-stablelists0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-core0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-core0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-debuginfo0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-devel0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-modules0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-modules-extra0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debuginfo0:4.18.0-553.97.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
rocky linux:kernel0:4.18.0-553.97.1.el8_10 · Rocky Linux:8Package registry (OSV)

+13

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records